Quality Loss using mpeg4modifier ?

[VALi]

Hey there.


Since all my own rips have the right Aspect, i never came across the Question of chaning ar without a complete reencode.

But browsing around forum i came across mpeg4modifier, and tried around a bit. First, it works fine. But second, i asked myself, if it wont "lower" quality or something.

for example :

a movie enconded to 512x288 (only 6mb file to test around),
but real aspect is 2,35. so i used mpeg4modifier to change movie to 640x272 and it works fine (beside when clicking file info, it still shows 512x288, but when start the clip, its 640x272).

Tho i ask myself, if this is quality loss or not, since
512x288 = 147456 pixel, and
640x272 = 174080 pixel, tho the "new" file has much more pixel, doesnt that lead to lower quality, since the "original" file was like "streched"?


thanks for all your answers

[celtic_druid]

Shouldn't that be 512x288-->677x288? Really upto the player though since MPEG4Modifier doesn't change/set the resolution.

Lower quality than actually encoding at 672x288? Well yes, but you don't really hear people complaining about anamorphic DVD's. Vertical resolution is more important, hence 512x288-->677x288. You don't want to reduce the vertical resolution from 288 to 272.

[Brother John]

MPEG4Modifier doesn't touch the video stream. It just sets the AR flag to the needed value. You video stays as 512x288 and is resized when playing it. So the answer to your question is: no. MPEG4Modifier doesn't affect quality at all.

[VALi]

ahhh, ok.. i get it.

thx for your answers. and yes, the new resolution was a bit weird, i just tested around to see if it works (and gets the video rid of the weird look, hence 1,85 wasn the right aspect)

to change my question : when playing a video encoded to 512x288 (hence "bad" look with weird heads and stuff) and "flagged by mpeg4modifier"(=now look on screen is ok) to 677x288 its quality will be lower then a encode to 640x272 with the same endsize ?
[lets say both files 90 min ->700mb, both xvid with the same settings]

ok, maybe teh question is a little bit to specific .. what i ask myself is .. when i encode a movie with the wrong aspect,
is it better for me to do a new encode with the right aspect, or will a similar quality be reached over editing with mpeg4modifier?
(i am VERy interested in perfect quality)

[Brother John]

Generally speaking:
Anamorphic encoding has its full advantage only when you keep the original resolution (only cropping). When you resize your video you should choose a square pixel resolution.

If you really aim for perfect quality, forget 1 CD target size. Go for 1/2 DVD-5 instead to take advantage of anamorphic resolution, low compression and probably enough space left for AC3 audio. Such encodings are not too likely to play on standalones without problems, though.